In general, a display device includes a display panel, gate-driving circuitry and data-driving circuitry. The display panel includes a thin film transistor array panel having gate lines, data lines, pixel electrodes and thin film transistors, an opposite panel having one or more common electrodes, and a liquid crystal layer provided between the two panels. The two panels are aligned and sealed by a sealant. The gate-driving circuitry and the data-driving circuitry are usually provided on a printed circuit board, or as integrated circuits connected to the display panel.
Recently, the gate-driving circuitry has been formed directly on the thin film transistor array panel in order to minimize device size and to increase efficiency. In such a structure, however, a parasitic capacitance is created between the gate-driving circuitry and the common electrode or electrodes on the opposite panel, which may cause the gate-driving circuitry to malfunction. Because the dielectric constant of the sealant is less than that of the liquid crystal molecules, it has been proposed to provide the sealant between the gate-driving circuitry and the opposite panel to reduce the parasitic capacitance.
As display devices become larger, the one-drop-filling (ODF) method is widely used with a photosetting sealant to provide the liquid crystal material between the two panels. The photosetting sealant, which holds the two panels, is hardened by exposure to light. The sealant is irradiated from the thin film transistor array panel side because an opaque layer is usually formed on the opposite panel facing the gate-driving circuitry. Irradiating from the thin film transistor array panel side, however, may lead to insufficient light to harden the sealant, especially when the width of a signal line, or a transistor, in the gate-driving circuitry, is larger than 100 μm. Consequently, the two panels may be susceptible to moisture entered through the insufficiently cured sealant, leading to corrosion in the gate-driving circuitry.
Accordingly, there is a need for a display device with gate driving circuitry that overcomes the disadvantages discussed above.